Near the surface of the Earth there is an electric field of about 150 V/m which points downward. Two identical balls with mass m = 0.540 kg are dropped from a height of 2.00 m, but one of the balls is positively charged with q_1 = 650 mu C and the second is negatively charged with q_2 = -650 mu C. Use conservation of energy to determine the difference in the speeds of the two balls when they hit the ground. (Neglect air resistance.)